There are some pages in Bessie's book ["Men in Battle"] which tell us more about the war in Spain, and in fact more about war in general, than whole volumes of parliamentary records. And this in spite of the fact that the author hardly ever generalizes, seldom mentions anything he did not see, and appears to write in almost unsullied political innocence.
I think this is one of the best war books I ever read. Its effects come directly from the material in an extraordinary way; it does not seem to be opaque, like most books, hiding from the reader just what the author most wishes to reveal. There are no "literary" effects at all, or, such as they are, the material creates them. The whole thing gives such a terrifying impression of exact truth that in its climactic passages … we lie there, we the readers, on that stony slope, and hide our heads beneath the moaning of the shells, and gasp with relief at each one that has gone safely by. This kind of short circuit in communication is one of the rarest phenomena, happens only occasionally even in the work of great writers, and is not likely to be achieved by any writer for long at a time….
Most of [the men in the International Brigades] believed in social revolution, and some did not, but all seem to have been convinced (at any rate to start with) that they fought not for Spain alone, but for the masses of their fellow men. There may have been great political naiveté in their ways of thinking and feeling, but there was also great human force. These are the exact values which were shattered at the outbreak of the present war, to be reassembled (if at all) in another pattern. To understand that process, which is so much bigger than the International Brigades ever were Bessie's book is a valuable help. But aside from its contribution to what we may understand of the course of events, it has its independent value as a powerful narrative, an almost unique document of human experience in war.
Vincent Sheean, "One of the Best War Books," in New York Herald Tribune Books (© I.H.T. Corporation; reprinted by permission), October 8, 1939, p. ix.